The prior art is replete with various types of electronic devices. For example, portable medical devices are useful for patients that have conditions that must be monitored on a continuous or frequent basis. In this regard, diabetics are usually required to modify and monitor their daily lifestyle to keep their blood glucose (BG) in balance. Some diabetics use portable insulin pump systems that are designed to deliver accurate and measured doses of insulin via infusion sets (an infusion set delivers the insulin through a small diameter tube that terminates at, e.g., a cannula inserted under the patient's skin). Portable insulin pumps are usually powered by either an alkaline battery, a lithium-ion battery, or a rechargeable battery.
One drawback with battery operated devices is the inability to utilize all of the energy stored in the battery due to the natural voltage decay associated with energy depletion. This particular problem is most prevalent with alkaline batteries, which tend to suffer a drop in voltage after a relatively short period of time even though an adequate amount of stored energy remains. Lithium and nickel-metal hydride (NiMH) batteries tend to maintain a more stable voltage over time, which generally allows for a higher percentage of the stored energy to be utilized, relative to the amount of stored energy typically utilized with alkaline batteries. Although lithium and NiMH batteries maintain a very stable voltage over time, they suffer from a sharp voltage drop at the end of life. Predicting when this drop will occur is very difficult and often requires a great deal of testing and characterization to allow for a sufficient user warning before the actual end of the battery life.
The remaining amount of battery life is often displayed on an electronic device in the form of a graphical icon, an indicator, a graph, or the like. Conventional battery life indicators used with consumer devices (e.g., mobile phones, digital media players, and video game devices) can be inaccurate and imprecise. Moreover, conventional battery life indicators may not use a proportional time scale for purposes of representing the remaining amount of battery life. For example, if the total lifespan of a replaceable battery is ten days for a given electronic device, a conventional battery life indicator might indicate full battery capacity for eight days, and thereafter indicate a quick decrease in battery capacity. Thus, it would be desirable to have a battery life indicator that accurately and proportionately indicates the remaining amount of battery life relative to actual runtime of the battery.